/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.valves;

import org.apache.catalina.AccessLog;
import org.apache.catalina.Globals;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

import javax.servlet.ServletException;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.regex.Pattern;

/**
 * <p>
 * Tomcat port of <a href="http://httpd.apache.org/docs/trunk/mod/mod_remoteip.html">mod_remoteip</a>, this valve replaces the apparent
 * client remote IP address and hostname for the request with the IP address list presented by a proxy or a load balancer via a request
 * headers (e.g. "X-Forwarded-For").
 * </p>
 * <p>
 * Another feature of this valve is to replace the apparent scheme (http/https) and server port with the scheme presented by a proxy or a
 * load balancer via a request header (e.g. "X-Forwarded-Proto").
 * </p>
 * <p>
 * This valve proceeds as follows:
 * </p>
 * <p>
 * If the incoming <code>request.getRemoteAddr()</code> matches the valve's list of internal proxies :
 * <ul>
 * <li>Loop on the comma delimited list of IPs and hostnames passed by the preceding load balancer or proxy in the given request's Http
 * header named <code>$remoteIpHeader</code> (default value <code>x-forwarded-for</code>). Values are processed in right-to-left order.</li>
 * <li>For each ip/host of the list:
 * <ul>
 * <li>if it matches the internal proxies list, the ip/host is swallowed</li>
 * <li>if it matches the trusted proxies list, the ip/host is added to the created proxies header</li>
 * <li>otherwise, the ip/host is declared to be the remote ip and looping is stopped.</li>
 * </ul>
 * </li>
 * <li>If the request http header named <code>$protocolHeader</code> (e.g. <code>x-forwarded-for</code>) equals to the value of
 * <code>protocolHeaderHttpsValue</code> configuration parameter (default <code>https</code>) then <code>request.isSecure = true</code>,
 * <code>request.scheme = https</code> and <code>request.serverPort = 443</code>. Note that 443 can be overwritten with the
 * <code>$httpsServerPort</code> configuration parameter.</li>
 * </ul>
 * </p>
 * <p>
 * <strong>Configuration parameters:</strong>
 * <table border="1">
 * <tr>
 * <th>RemoteIpValve property</th>
 * <th>Description</th>
 * <th>Equivalent mod_remoteip directive</th>
 * <th>Format</th>
 * <th>Default Value</th>
 * </tr>
 * <tr>
 * <td>remoteIpHeader</td>
 * <td>Name of the Http Header read by this valve that holds the list of traversed IP addresses starting from the requesting client</td>
 * <td>RemoteIPHeader</td>
 * <td>Compliant http header name</td>
 * <td>x-forwarded-for</td>
 * </tr>
 * <tr>
 * <td>internalProxies</td>
 * <td>Regular expression that matches the IP addresses of internal proxies.
 * If they appear in the <code>remoteIpHeader</code> value, they will be
 * trusted and will not appear
 * in the <code>proxiesHeader</code> value</td>
 * <td>RemoteIPInternalProxy</td>
 * <td>Regular expression (in the syntax supported by
 * {@link java.util.regex.Pattern java.util.regex})</td>
 * <td>10\.\d{1,3}\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|169\.254\.\d{1,3}\.\d{1,3}|127\.\d{1,3}\.\d{1,3}\.\d{1,3}<br/>
 * By default, 10/8, 192.168/16, 169.254/16 and 127/8 are allowed ; 172.16/12 has not been enabled by default because it is complex to
 * describe with regular expressions</td>
 * </tr>
 * </tr>
 * <tr>
 * <td>proxiesHeader</td>
 * <td>Name of the http header created by this valve to hold the list of proxies that have been processed in the incoming
 * <code>remoteIpHeader</code></td>
 * <td>proxiesHeader</td>
 * <td>Compliant http header name</td>
 * <td>x-forwarded-by</td>
 * </tr>
 * <tr>
 * <td>trustedProxies</td>
 * <td>Regular expression that matches the IP addresses of trusted proxies.
 * If they appear in the <code>remoteIpHeader</code> value, they will be
 * trusted and will appear in the <code>proxiesHeader</code> value</td>
 * <td>RemoteIPTrustedProxy</td>
 * <td>Regular expression (in the syntax supported by
 * {@link java.util.regex.Pattern java.util.regex})</td>
 * <td>&nbsp;</td>
 * </tr>
 * <tr>
 * <td>protocolHeader</td>
 * <td>Name of the http header read by this valve that holds the flag that this request </td>
 * <td>N/A</td>
 * <td>Compliant http header name like <code>X-Forwarded-Proto</code>, <code>X-Forwarded-Ssl</code> or <code>Front-End-Https</code></td>
 * <td><code>null</code></td>
 * </tr>
 * <tr>
 * <td>protocolHeaderHttpsValue</td>
 * <td>Value of the <code>protocolHeader</code> to indicate that it is an Https request</td>
 * <td>N/A</td>
 * <td>String like <code>https</code> or <code>ON</code></td>
 * <td><code>https</code></td>
 * </tr>
 * <tr>
 * <td>httpServerPort</td>
 * <td>Value returned by {@link javax.servlet.ServletRequest#getServerPort()} when the <code>protocolHeader</code> indicates <code>http</code> protocol</td>
 * <td>N/A</td>
 * <td>integer</td>
 * <td>80</td>
 * </tr>
 * <tr>
 * <td>httpsServerPort</td>
 * <td>Value returned by {@link javax.servlet.ServletRequest#getServerPort()} when the <code>protocolHeader</code> indicates <code>https</code> protocol</td>
 * <td>N/A</td>
 * <td>integer</td>
 * <td>443</td>
 * </tr>
 * </table>
 * </p>
 * <p>
 * <p>
 * This Valve may be attached to any Container, depending on the granularity of the filtering you wish to perform.
 * </p>
 * <p>
 * <strong>Regular expression vs. IP address blocks:</strong> <code>mod_remoteip</code> allows to use address blocks (e.g.
 * <code>192.168/16</code>) to configure <code>RemoteIPInternalProxy</code> and <code>RemoteIPTrustedProxy</code> ; as Tomcat doesn't have a
 * library similar to <a
 * href="http://apr.apache.org/docs/apr/1.3/group__apr__network__io.html#gb74d21b8898b7c40bf7fd07ad3eb993d">apr_ipsubnet_test</a>,
 * <code>RemoteIpValve</code> uses regular expression to configure <code>internalProxies</code> and <code>trustedProxies</code> in the same
 * fashion as {@link RequestFilterValve} does.
 * </p>
 * <hr/>
 * <p>
 * <strong>Sample with internal proxies</strong>
 * </p>
 * <p>
 * RemoteIpValve configuration:
 * </p>
 * <code><pre>
 * &lt;Valve
 *   className="org.apache.catalina.valves.RemoteIpValve"
 *   internalProxies="192\.168\.0\.10|192\.168\.0\.11"
 *   remoteIpHeader="x-forwarded-for"
 *   proxiesHeader="x-forwarded-by"
 *   protocolHeader="x-forwarded-proto"
 *   /&gt;</pre></code>
 * <p>
 * Request values:
 * <table border="1">
 * <tr>
 * <th>property</th>
 * <th>Value Before RemoteIpValve</th>
 * <th>Value After RemoteIpValve</th>
 * </tr>
 * <tr>
 * <td>request.remoteAddr</td>
 * <td>192.168.0.10</td>
 * <td>140.211.11.130</td>
 * </tr>
 * <tr>
 * <td>request.header['x-forwarded-for']</td>
 * <td>140.211.11.130, 192.168.0.10</td>
 * <td>null</td>
 * </tr>
 * <tr>
 * <td>request.header['x-forwarded-by']</td>
 * <td>null</td>
 * <td>null</td>
 * </tr>
 * <tr>
 * <td>request.header['x-forwarded-proto']</td>
 * <td>https</td>
 * <td>https</td>
 * </tr>
 * <tr>
 * <td>request.scheme</td>
 * <td>http</td>
 * <td>https</td>
 * </tr>
 * <tr>
 * <td>request.secure</td>
 * <td>false</td>
 * <td>true</td>
 * </tr>
 * <tr>
 * <td>request.serverPort</td>
 * <td>80</td>
 * <td>443</td>
 * </tr>
 * </table>
 * Note : <code>x-forwarded-by</code> header is null because only internal proxies as been traversed by the request.
 * <code>x-forwarded-by</code> is null because all the proxies are trusted or internal.
 * </p>
 * <hr/>
 * <p>
 * <strong>Sample with trusted proxies</strong>
 * </p>
 * <p>
 * RemoteIpValve configuration:
 * </p>
 * <code><pre>
 * &lt;Valve
 *   className="org.apache.catalina.valves.RemoteIpValve"
 *   internalProxies="192\.168\.0\.10|192\.168\.0\.11"
 *   remoteIpHeader="x-forwarded-for"
 *   proxiesHeader="x-forwarded-by"
 *   trustedProxies="proxy1|proxy2"
 *   /&gt;</pre></code>
 * <p>
 * Request values:
 * <table border="1">
 * <tr>
 * <th>property</th>
 * <th>Value Before RemoteIpValve</th>
 * <th>Value After RemoteIpValve</th>
 * </tr>
 * <tr>
 * <td>request.remoteAddr</td>
 * <td>192.168.0.10</td>
 * <td>140.211.11.130</td>
 * </tr>
 * <tr>
 * <td>request.header['x-forwarded-for']</td>
 * <td>140.211.11.130, proxy1, proxy2</td>
 * <td>null</td>
 * </tr>
 * <tr>
 * <td>request.header['x-forwarded-by']</td>
 * <td>null</td>
 * <td>proxy1, proxy2</td>
 * </tr>
 * </table>
 * Note : <code>proxy1</code> and <code>proxy2</code> are both trusted proxies that come in <code>x-forwarded-for</code> header, they both
 * are migrated in <code>x-forwarded-by</code> header. <code>x-forwarded-by</code> is null because all the proxies are trusted or internal.
 * </p>
 * <hr/>
 * <p>
 * <strong>Sample with internal and trusted proxies</strong>
 * </p>
 * <p>
 * RemoteIpValve configuration:
 * </p>
 * <code><pre>
 * &lt;Valve
 *   className="org.apache.catalina.valves.RemoteIpValve"
 *   internalProxies="192\.168\.0\.10|192\.168\.0\.11"
 *   remoteIpHeader="x-forwarded-for"
 *   proxiesHeader="x-forwarded-by"
 *   trustedProxies="proxy1|proxy2"
 *   /&gt;</pre></code>
 * <p>
 * Request values:
 * <table border="1">
 * <tr>
 * <th>property</th>
 * <th>Value Before RemoteIpValve</th>
 * <th>Value After RemoteIpValve</th>
 * </tr>
 * <tr>
 * <td>request.remoteAddr</td>
 * <td>192.168.0.10</td>
 * <td>140.211.11.130</td>
 * </tr>
 * <tr>
 * <td>request.header['x-forwarded-for']</td>
 * <td>140.211.11.130, proxy1, proxy2, 192.168.0.10</td>
 * <td>null</td>
 * </tr>
 * <tr>
 * <td>request.header['x-forwarded-by']</td>
 * <td>null</td>
 * <td>proxy1, proxy2</td>
 * </tr>
 * </table>
 * Note : <code>proxy1</code> and <code>proxy2</code> are both trusted proxies that come in <code>x-forwarded-for</code> header, they both
 * are migrated in <code>x-forwarded-by</code> header. As <code>192.168.0.10</code> is an internal proxy, it does not appear in
 * <code>x-forwarded-by</code>. <code>x-forwarded-by</code> is null because all the proxies are trusted or internal.
 * </p>
 * <hr/>
 * <p>
 * <strong>Sample with an untrusted proxy</strong>
 * </p>
 * <p>
 * RemoteIpValve configuration:
 * </p>
 * <code><pre>
 * &lt;Valve
 *   className="org.apache.catalina.valves.RemoteIpValve"
 *   internalProxies="192\.168\.0\.10|192\.168\.0\.11"
 *   remoteIpHeader="x-forwarded-for"
 *   proxiesHeader="x-forwarded-by"
 *   trustedProxies="proxy1|proxy2"
 *   /&gt;</pre></code>
 * <p>
 * Request values:
 * <table border="1">
 * <tr>
 * <th>property</th>
 * <th>Value Before RemoteIpValve</th>
 * <th>Value After RemoteIpValve</th>
 * </tr>
 * <tr>
 * <td>request.remoteAddr</td>
 * <td>192.168.0.10</td>
 * <td>untrusted-proxy</td>
 * </tr>
 * <tr>
 * <td>request.header['x-forwarded-for']</td>
 * <td>140.211.11.130, untrusted-proxy, proxy1</td>
 * <td>140.211.11.130</td>
 * </tr>
 * <tr>
 * <td>request.header['x-forwarded-by']</td>
 * <td>null</td>
 * <td>proxy1</td>
 * </tr>
 * </table>
 * Note : <code>x-forwarded-by</code> holds the trusted proxy <code>proxy1</code>. <code>x-forwarded-by</code> holds
 * <code>140.211.11.130</code> because <code>untrusted-proxy</code> is not trusted and thus, we can not trust that
 * <code>untrusted-proxy</code> is the actual remote ip. <code>request.remoteAddr</code> is <code>untrusted-proxy</code> that is an IP
 * verified by <code>proxy1</code>.
 * </p>
 */
public class RemoteIpValve extends ValveBase {

	/**
	 * {@link Pattern} for a comma delimited string that support whitespace characters
	 */
	private static final Pattern commaSeparatedValuesPattern = Pattern.compile("\\s*,\\s*");

	/**
	 * The descriptive information related to this implementation.
	 */
	private static final String info = "org.apache.catalina.valves.RemoteIpValve/1.0";

	/**
	 * Logger
	 */
	private static final Log log = LogFactory.getLog(RemoteIpValve.class);
	/**
	 * @see #setHttpServerPort(int)
	 */
	private int httpServerPort = 80;
	/**
	 * @see #setHttpsServerPort(int)
	 */
	private int httpsServerPort = 443;
	private boolean changeLocalPort = false;
	/**
	 * @see #setInternalProxies(String)
	 */
	private Pattern internalProxies = Pattern.compile(
			"10\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}|" +
					"192\\.168\\.\\d{1,3}\\.\\d{1,3}|" +
					"169\\.254\\.\\d{1,3}\\.\\d{1,3}|" +
					"127\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}");
	/**
	 * @see #setProtocolHeader(String)
	 */
	private String protocolHeader = null;
	/**
	 * @see #setProtocolHeaderHttpsValue(String)
	 */
	private String protocolHeaderHttpsValue = "https";
	private String portHeader = null;
	/**
	 * @see #setProxiesHeader(String)
	 */
	private String proxiesHeader = "X-Forwarded-By";
	/**
	 * @see #setRemoteIpHeader(String)
	 */
	private String remoteIpHeader = "X-Forwarded-For";
	/**
	 * @see #setRequestAttributesEnabled(boolean)
	 */
	private boolean requestAttributesEnabled = true;
	/**
	 * @see RemoteIpValve#setTrustedProxies(String)
	 */
	private Pattern trustedProxies = null;

	/**
	 * Default constructor that ensures {@link ValveBase#ValveBase(boolean)} is
	 * called with <code>true</code>.
	 */
	public RemoteIpValve() {
		// Async requests are supported with this valve
		super(true);
	}

	/**
	 * Convert a given comma delimited String into an array of String
	 *
	 * @return array of String (non <code>null</code>)
	 */
	protected static String[] commaDelimitedListToStringArray(String commaDelimitedStrings) {
		return (commaDelimitedStrings == null || commaDelimitedStrings.length() == 0) ? new String[0] : commaSeparatedValuesPattern
				.split(commaDelimitedStrings);
	}

	/**
	 * Convert an array of strings in a comma delimited string
	 */
	protected static String listToCommaDelimitedString(List<String> stringList) {
		if (stringList == null) {
			return "";
		}
		StringBuilder result = new StringBuilder();
		for (Iterator<String> it = stringList.iterator(); it.hasNext(); ) {
			Object element = it.next();
			if (element != null) {
				result.append(element);
				if (it.hasNext()) {
					result.append(", ");
				}
			}
		}
		return result.toString();
	}

	public int getHttpsServerPort() {
		return httpsServerPort;
	}

	/**
	 * <p>
	 * Server Port value if the {@link #protocolHeader} indicates HTTPS
	 * </p>
	 * <p>
	 * Default value : 443
	 * </p>
	 */
	public void setHttpsServerPort(int httpsServerPort) {
		this.httpsServerPort = httpsServerPort;
	}

	public int getHttpServerPort() {
		return httpServerPort;
	}

	/**
	 * <p>
	 * Server Port value if the {@link #protocolHeader} is not <code>null</code> and does not indicate HTTP
	 * </p>
	 * <p>
	 * Default value : 80
	 * </p>
	 */
	public void setHttpServerPort(int httpServerPort) {
		this.httpServerPort = httpServerPort;
	}

	public boolean isChangeLocalPort() {
		return changeLocalPort;
	}

	public void setChangeLocalPort(boolean changeLocalPort) {
		this.changeLocalPort = changeLocalPort;
	}

	/**
	 * Obtain the name of the HTTP header used to override the value returned
	 * by {@link Request#getServerPort()} and (optionally depending on {link
	 * {@link #isChangeLocalPort()} {@link Request#getLocalPort()}.
	 *
	 * @return The HTTP header name
	 */
	public String getPortHeader() {
		return portHeader;
	}

	/**
	 * Set the name of the HTTP header used to override the value returned
	 * by {@link Request#getServerPort()} and (optionally depending on {link
	 * {@link #isChangeLocalPort()} {@link Request#getLocalPort()}.
	 *
	 * @param portHeader The HTTP header name
	 */
	public void setPortHeader(String portHeader) {
		this.portHeader = portHeader;
	}

	/**
	 * Return descriptive information about this Valve implementation.
	 */
	@Override
	public String getInfo() {
		return info;
	}

	/**
	 * @return Regular expression that defines the internal proxies
	 * @see #setInternalProxies(String)
	 */
	public String getInternalProxies() {
		if (internalProxies == null) {
			return null;
		}
		return internalProxies.toString();
	}

	/**
	 * <p>
	 * Regular expression that defines the internal proxies.
	 * </p>
	 * <p>
	 * Default value : 10\.\d{1,3}\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|169\.254.\d{1,3}.\d{1,3}|127\.\d{1,3}\.\d{1,3}\.\d{1,3}
	 * </p>
	 */
	public void setInternalProxies(String internalProxies) {
		if (internalProxies == null || internalProxies.length() == 0) {
			this.internalProxies = null;
		} else {
			this.internalProxies = Pattern.compile(internalProxies);
		}
	}

	/**
	 * @return the protocol header (e.g. "X-Forwarded-Proto")
	 * @see #setProtocolHeader(String)
	 */
	public String getProtocolHeader() {
		return protocolHeader;
	}

	/**
	 * <p>
	 * Header that holds the incoming protocol, usually named <code>X-Forwarded-Proto</code>. If <code>null</code>, request.scheme and
	 * request.secure will not be modified.
	 * </p>
	 * <p>
	 * Default value : <code>null</code>
	 * </p>
	 */
	public void setProtocolHeader(String protocolHeader) {
		this.protocolHeader = protocolHeader;
	}

	/**
	 * @return the value of the protocol header for incoming https request (e.g. "https")
	 * @see RemoteIpValve#setProtocolHeaderHttpsValue(String)
	 */
	public String getProtocolHeaderHttpsValue() {
		return protocolHeaderHttpsValue;
	}

	/**
	 * <p>
	 * Case insensitive value of the protocol header to indicate that the incoming http request uses SSL.
	 * </p>
	 * <p>
	 * Default value : <code>https</code>
	 * </p>
	 */
	public void setProtocolHeaderHttpsValue(String protocolHeaderHttpsValue) {
		this.protocolHeaderHttpsValue = protocolHeaderHttpsValue;
	}

	/**
	 * @return the proxies header name (e.g. "X-Forwarded-By")
	 * @see #setProxiesHeader(String)
	 */
	public String getProxiesHeader() {
		return proxiesHeader;
	}

	/**
	 * <p>
	 * The proxiesHeader directive specifies a header into which mod_remoteip will collect a list of all of the intermediate client IP
	 * addresses trusted to resolve the actual remote IP. Note that intermediate RemoteIPTrustedProxy addresses are recorded in this header,
	 * while any intermediate RemoteIPInternalProxy addresses are discarded.
	 * </p>
	 * <p>
	 * Name of the http header that holds the list of trusted proxies that has been traversed by the http request.
	 * </p>
	 * <p>
	 * The value of this header can be comma delimited.
	 * </p>
	 * <p>
	 * Default value : <code>X-Forwarded-By</code>
	 * </p>
	 */
	public void setProxiesHeader(String proxiesHeader) {
		this.proxiesHeader = proxiesHeader;
	}

	/**
	 * @return the remote IP header name (e.g. "X-Forwarded-For")
	 * @see #setRemoteIpHeader(String)
	 */
	public String getRemoteIpHeader() {
		return remoteIpHeader;
	}

	/**
	 * <p>
	 * Name of the http header from which the remote ip is extracted.
	 * </p>
	 * <p>
	 * The value of this header can be comma delimited.
	 * </p>
	 * <p>
	 * Default value : <code>X-Forwarded-For</code>
	 * </p>
	 *
	 * @param remoteIpHeader
	 */
	public void setRemoteIpHeader(String remoteIpHeader) {
		this.remoteIpHeader = remoteIpHeader;
	}

	/**
	 * @return <code>true</code> if the attributes will be logged, otherwise
	 * <code>false</code>
	 * @see #setRequestAttributesEnabled(boolean)
	 */
	public boolean getRequestAttributesEnabled() {
		return requestAttributesEnabled;
	}

	/**
	 * Should this valve set request attributes for IP address, Hostname,
	 * protocol and port used for the request? This are typically used in
	 * conjunction with the {@link AccessLog} which will otherwise log the
	 * original values. Default is <code>true</code>.
	 * <p>
	 * The attributes set are:
	 * <ul>
	 * <li>org.apache.catalina.AccessLog.RemoteAddr</li>
	 * <li>org.apache.catalina.AccessLog.RemoteHost</li>
	 * <li>org.apache.catalina.AccessLog.Protocol</li>
	 * <li>org.apache.catalina.AccessLog.ServerPort</li>
	 * <li>org.apache.tomcat.remoteAddr</li>
	 * </ul>
	 *
	 * @param requestAttributesEnabled <code>true</code> causes the attributes
	 *                                 to be set, <code>false</code> disables
	 *                                 the setting of the attributes.
	 */
	public void setRequestAttributesEnabled(boolean requestAttributesEnabled) {
		this.requestAttributesEnabled = requestAttributesEnabled;
	}

	/**
	 * @return Regular expression that defines the trusted proxies
	 * @see #setTrustedProxies(String)
	 */
	public String getTrustedProxies() {
		if (trustedProxies == null) {
			return null;
		}
		return trustedProxies.toString();
	}

	/**
	 * <p>
	 * Regular expression defining proxies that are trusted when they appear in
	 * the {@link #remoteIpHeader} header.
	 * </p>
	 * <p>
	 * Default value : empty list, no external proxy is trusted.
	 * </p>
	 */
	public void setTrustedProxies(String trustedProxies) {
		if (trustedProxies == null || trustedProxies.length() == 0) {
			this.trustedProxies = null;
		} else {
			this.trustedProxies = Pattern.compile(trustedProxies);
		}
	}

	/**
	 * {@inheritDoc}
	 */
	@Override
	public void invoke(Request request, Response response) throws IOException, ServletException {
		final String originalRemoteAddr = request.getRemoteAddr();
		final String originalRemoteHost = request.getRemoteHost();
		final String originalScheme = request.getScheme();
		final boolean originalSecure = request.isSecure();
		final int originalServerPort = request.getServerPort();

		if (internalProxies != null &&
				internalProxies.matcher(originalRemoteAddr).matches()) {
			String remoteIp = null;
			// In java 6, proxiesHeaderValue should be declared as a java.util.Deque
			LinkedList<String> proxiesHeaderValue = new LinkedList<String>();
			StringBuilder concatRemoteIpHeaderValue = new StringBuilder();

			for (Enumeration<String> e = request.getHeaders(remoteIpHeader); e.hasMoreElements(); ) {
				if (concatRemoteIpHeaderValue.length() > 0) {
					concatRemoteIpHeaderValue.append(", ");
				}

				concatRemoteIpHeaderValue.append(e.nextElement());
			}

			String[] remoteIpHeaderValue = commaDelimitedListToStringArray(concatRemoteIpHeaderValue.toString());
			int idx;
			// loop on remoteIpHeaderValue to find the first trusted remote ip and to build the proxies chain
			for (idx = remoteIpHeaderValue.length - 1; idx >= 0; idx--) {
				String currentRemoteIp = remoteIpHeaderValue[idx];
				remoteIp = currentRemoteIp;
				if (internalProxies.matcher(currentRemoteIp).matches()) {
					// do nothing, internalProxies IPs are not appended to the
				} else if (trustedProxies != null &&
						trustedProxies.matcher(currentRemoteIp).matches()) {
					proxiesHeaderValue.addFirst(currentRemoteIp);
				} else {
					idx--; // decrement idx because break statement doesn't do it
					break;
				}
			}
			// continue to loop on remoteIpHeaderValue to build the new value of the remoteIpHeader
			LinkedList<String> newRemoteIpHeaderValue = new LinkedList<String>();
			for (; idx >= 0; idx--) {
				String currentRemoteIp = remoteIpHeaderValue[idx];
				newRemoteIpHeaderValue.addFirst(currentRemoteIp);
			}
			if (remoteIp != null) {

				request.setRemoteAddr(remoteIp);
				request.setRemoteHost(remoteIp);

				// use request.coyoteRequest.mimeHeaders.setValue(str).setString(str) because request.addHeader(str, str) is no-op in Tomcat
				// 6.0
				if (proxiesHeaderValue.size() == 0) {
					request.getCoyoteRequest().getMimeHeaders().removeHeader(proxiesHeader);
				} else {
					String commaDelimitedListOfProxies = listToCommaDelimitedString(proxiesHeaderValue);
					request.getCoyoteRequest().getMimeHeaders().setValue(proxiesHeader).setString(commaDelimitedListOfProxies);
				}
				if (newRemoteIpHeaderValue.size() == 0) {
					request.getCoyoteRequest().getMimeHeaders().removeHeader(remoteIpHeader);
				} else {
					String commaDelimitedRemoteIpHeaderValue = listToCommaDelimitedString(newRemoteIpHeaderValue);
					request.getCoyoteRequest().getMimeHeaders().setValue(remoteIpHeader).setString(commaDelimitedRemoteIpHeaderValue);
				}
			}

			if (protocolHeader != null) {
				String protocolHeaderValue = request.getHeader(protocolHeader);
				if (protocolHeaderValue == null) {
					// don't modify the secure,scheme and serverPort attributes
					// of the request
				} else if (protocolHeaderHttpsValue.equalsIgnoreCase(protocolHeaderValue)) {
					request.setSecure(true);
					// use request.coyoteRequest.scheme instead of request.setScheme() because request.setScheme() is no-op in Tomcat 6.0
					request.getCoyoteRequest().scheme().setString("https");

					setPorts(request, httpsServerPort);
				} else {
					request.setSecure(false);
					// use request.coyoteRequest.scheme instead of request.setScheme() because request.setScheme() is no-op in Tomcat 6.0
					request.getCoyoteRequest().scheme().setString("http");

					setPorts(request, httpServerPort);
				}
			}

			if (log.isDebugEnabled()) {
				log.debug("Incoming request " + request.getRequestURI() + " with originalRemoteAddr '" + originalRemoteAddr
						+ "', originalRemoteHost='" + originalRemoteHost + "', originalSecure='" + originalSecure + "', originalScheme='"
						+ originalScheme + "' will be seen as newRemoteAddr='" + request.getRemoteAddr() + "', newRemoteHost='"
						+ request.getRemoteHost() + "', newScheme='" + request.getScheme() + "', newSecure='" + request.isSecure() + "'");
			}
		} else {
			if (log.isDebugEnabled()) {
				log.debug("Skip RemoteIpValve for request " + request.getRequestURI() + " with originalRemoteAddr '"
						+ request.getRemoteAddr() + "'");
			}
		}
		if (requestAttributesEnabled) {
			request.setAttribute(AccessLog.REMOTE_ADDR_ATTRIBUTE,
					request.getRemoteAddr());
			request.setAttribute(Globals.REMOTE_ADDR_ATTRIBUTE,
					request.getRemoteAddr());
			request.setAttribute(AccessLog.REMOTE_HOST_ATTRIBUTE,
					request.getRemoteHost());
			request.setAttribute(AccessLog.PROTOCOL_ATTRIBUTE,
					request.getProtocol());
			request.setAttribute(AccessLog.SERVER_PORT_ATTRIBUTE,
					Integer.valueOf(request.getServerPort()));
		}
		try {
			getNext().invoke(request, response);
		} finally {
			request.setRemoteAddr(originalRemoteAddr);
			request.setRemoteHost(originalRemoteHost);

			request.setSecure(originalSecure);

			// use request.coyoteRequest.scheme instead of request.setScheme() because request.setScheme() is no-op in Tomcat 6.0
			request.getCoyoteRequest().scheme().setString(originalScheme);

			request.setServerPort(originalServerPort);
		}
	}

	private void setPorts(Request request, int defaultPort) {
		int port = defaultPort;
		if (portHeader != null) {
			String portHeaderValue = request.getHeader(portHeader);
			if (portHeaderValue != null) {
				try {
					port = Integer.parseInt(portHeaderValue);
				} catch (NumberFormatException nfe) {
					if (log.isDebugEnabled()) {
						log.debug(sm.getString(
								"remoteIpValve.invalidPortHeader",
								portHeaderValue, portHeader), nfe);
					}
				}
			}
		}
		request.setServerPort(port);
		if (changeLocalPort) {
			request.setLocalPort(port);
		}
	}
}
